Scanner

ABSTRACT

The invention relates to a scanner, in particular for the detection of one-dimensional and/or two-dimensional codes, having a light receiver arranged in a housing and an optical receiving system associated therewith and also accommodated in the housing, wherein at least one light source is additionally provided in the housing to illuminate the region to be scanned arranged in a scanning plane.

[0001] The invention relates to a scanner, in particular for thedetection of one-dimensional and/or two-dimensional codes, having alight receiver arranged in a housing and an optical receiving systemassociated therewith and also accommodated in the housing.

[0002] Such scanners known from the state of the art, can be formed, forexample as line scanners in order to be able to read barcodes in thisway without a relative movement having to be made between the scannerand the code. Such scanners can, however, also be utilized for thereading of two-dimensional codes provided that a relative movement isgenerated between the scanner and the code by means, for example, of aconveying motion. Alternatively, it is moreover also possible to usearea scanners known from the state of the art instead of a line scanner,with said area scanners being able to read two-dimensional codes withouta relative movement between the scanner and the code.

[0003] Known scanners based on the functional principle described abovehave the disadvantage that codes are frequently only recognizedincompletely or incorrectly or, in extreme cases, not at all as a resultof inadequate or changing light conditions.

[0004] An object of the present invention comprises the furtherdevelopment of a scanner of the initially named kind such that readingerrors caused by inadequate or changing light conditions can be at leastlargely excluded and in particular fully excluded.

[0005] This object is satisfied in accordance with the invention by atleast one light source being additionally provided in the housing toilluminate the region to be scanned arranged in an object plane.

[0006] Since the scanner has its own light source in accordance with theinvention which provides an optimum illumination of the region to bescanned or of the code to be read, the influence of the ambient lightconditions is at least largely eliminated, which means that the codescan also be read reliably and correctly in a dark environment or in anenvironment with changing light conditions.

[0007] It is preferred for the light source to be designed to transmit aconstant light intensity so that a continuous illumination is ensuredwhich is constant during the reading procedure.

[0008] It is furthermore of advantage if the light source is formed byat least one laser diode since such a point light source allows a goodbeam formation.

[0009] It is preferred for an optical transmitting system to beassociated with the light source, with said transmitting optical systemtransforming a substantially homocentric light bundle transmitted by thelight source into a substantially linear light beam focussed on theobject plane. When the scanner in accordance with the invention is usedas a linear scanner, this measure ensures that at least a large part ofthe light energy transmitted from the light source is concentrated onthe respective line to be read by the scanner, so that the line to bescanned is ideally illuminated. The optical transmitting systempreferably consists of refractive, diffractive and/or holographicelements.

[0010] The intensity of the linear light beam can have a Gaussiandistribution along the illuminated line. In this case, when a pluralityof light sources are provided, skilful overlapping of the lines whichare aligned to one another can be used to ensure that a relatively largeline region is constantly illuminated.

[0011] To allow different distances to be set between the scanner andthe object plane, i.e. different reading distances and/or different codesizes, the light source and/or the optical receiving system can bemovably held in the housing and be adjustable to different positions,with it being particularly advantageous for the movements of the lightsource and the optical receiving system to be mechanically correlatedwith one another so that the user must, for example, only actuate oneadjusting screw in order to move the light source and optical receivingsystem simultaneously and in a manner matched to each another such that,on the one hand, the optical receiving system is focused on the scanningplane and, on the other hand, an optimum illumination of the region tobe scanned in the scanning plane is ensured.

[0012] In order to realize the said adjustment possibilities, thereception optics can be displaceable along its optical axis.Furthermore, the light source can be pivotably formed in a first planewhich extends at least substantially parallel to the optical axes of thetransmission and optical receiving system. It is possible due to thesetwo adjustment possibilities to adapt the scanner in accordance with theinvention to different reading distances and different code sizes.

[0013] However, it is moreover, also possible to mature the light sourcepivotable in a second plane substantially perpendicular to the saidfirst plane, with this second plane including the optical axis of theoptical transmitting system. This adjustment makes it possible toachieve a situation in which, for example, when a linear light beam istransmitted, this light beam can be adjusted, in the scanning plane,perpendicular to the line of light generated in the scanning plane, andcan in particular be aligned with a further line of light.

[0014] It is particularly preferred if two units positioned with theiroptical axes at an angle to one another and consisting of one lightsource each and one optical transmitting system each are provided in thehousing of the scanner in accordance with the invention. An even betterillumination of the region to be scanned can be achieved by theprovision of two or more light sources.

[0015] An embodiment of the invention having two light sources, whicheach generate a linear light beam, is explained in more detail belowwith reference to the description of the figures.

[0016] The light receiver can be formed as a spatial resolutiondetector, in particular as a CCD array, CCD area, CMOS array or CMOSarea.

[0017] Further preferred embodiments are described in the dependentclaims. The invention is explained below by way of an embodiment withreference to the figures, in which are shown:

[0018]FIG. 1 a plan view of a scanner in accordance with the inventionwith the housing cover removed in which the essential components for theinvention are shown schematically; and

[0019]FIG. 2 a side view of the scanner in accordance with FIG. 1 withthe housing cover in place.

[0020] The scanner of FIG. 1 in accordance with the invention has asubstantially rectangular housing 1 which has a mount for a window 2 atone of its longer narrow sides. This window 2 is positioned obliquely toavoid interfering reflections. This oblique position can be seen inparticular from FIG. 2.

[0021] A circuit board 4, on which a light receiver or sensor 5 isarranged, is mounted in parallel alignment to the narrow side 3 in theregion of the narrow side 3 of the housing 1 opposite the window 2. Thecircuit board 4 is screwed to two webs 6 extending perpendicular to it.The webs 6 are in turn, for example, components of the housing 1. Thewebs 6 can be made together with the housing in a single injectionmolding procedure. The webs 6 extend over a large part of the housingwidth and also over a large part of the housing thickness extendingperpendicular to the drawing plane in accordance with FIG. 1 in order tothus create an optical separation between the light receiver 5 and thelight transmitters which are described in the following. This opticalseparation can naturally also be optimized by the webs 6 at the insideof the housing 1 extending over the whole housing thickness.

[0022] A receiving lens 7 is arranged between the two webs 6 and betweenthe light receiver 5 and the window 2, and said receiving lens 7 ismovably held along its optical axis A and is adjustably held atdifferent positions in the housing 1. A band-pass filter (not shown) canoptionally be interposed before or after the lens 7 in order to filterthe respectively interesting frequencies from the light received.

[0023] A carrier member 8 is provided at both sides of the optical axisA outside the region bounded by the two webs 6, and a laser diode 9, acollimator lens 10 and a cylinder lens 11 are each arranged thereon. Thecylinder lens 11 has in each case the function of transforming the lighttransmitted from the laser diode 9 and passed through the collimatorlens 10 from a point-focused light beam into a linearly focused lightbeam. The linear light beams or light lines transmitted from the twounits 9, 10, 11 are aligned with one another and focused to overlap oneanother at a scanning plane 12 inside which a code 13 to be read islocated. The lens 7 is also focused on this scanning plane 12.

[0024] The intensity of each light line has a Gaussian distributionalong each illuminated line in each of the two light beams, as is drawnin with a broken line in FIG. 1. The overlapping of the two light linesis selected such that a substantially energetically constantillumination results over the whole length of the commonly generatedilluminated line of light due to the addition of the two Gaussian energydistributions.

[0025] The two carrier members 8 are supported in housing 1 such thatthey are pivotable in a plane extending parallel to the plane of drawingin FIG. 1 and thus also parallel to the optical axes of the opticaltransmitting systems 10, 11 and the receiving lens 7. The angle αbetween the optical axis of the receiving lens 7 and the optical axes ofthe optical transmitting systems 10, 11 can be adjusted by this pivotalmovement such that ultimately different distances can be set between thehousing 1 and the object plane 12.

[0026] The carrier members 8 can moreover be pivotable in a planeextending perpendicular to the plane of drawing, said plane including ineach case the optical axis of the optical transmitting system 10, 11 inorder to align the two generated light lines with one another. It canalso be ensured by this adjustment possibility that the illuminated linein the scanning plane 12 is congruent with that line which is imaged onthe light receiver 5 by the lens 7. An additional possibility to alignthe two generated light lines can be obtained by the carrier members 8each also being rotatably supported around the optical axes of theirrespective optical transmitting systems 10, 11.

[0027] A scanner is thus provided by the arrangement in accordance withFIGS. 1 and 2 which actively illuminates a code to be read with a lineof light energetically largely constant over its length so that aproblem-free reading of the code via the receiving lens 7 becomespossible.

Reference Numeral List

[0028]1 housing

[0029]2 window

[0030]3 narrow side

[0031]4 platen

[0032]5 light receiver

[0033]6 webs

[0034]7 receiving lens

[0035]8 carrier member

[0036]9 laser diode

[0037]10 collimator lens

[0038]11 cylinder lens

[0039]12 object or scanning plane

[0040]13 code

1. A scanner, in particular for the detection of one-dimensional and/ortwo-dimensional codes (13), having a light receiver (5) arranged in ahousing (1) and an optical receiving system (7) associated therewith andalso accommodated in the housing (1), characterized in that at least onelight source (9) is additionally provided in the housing (1) toilluminate the region to be scanned arranged in an object plane (12). 2.A scanner in accordance with claim 1 , characterized in that the lightsource (9) is designed to transmit a constant light intensity.
 3. Ascanner in accordance with claim 1 , characterized in that the lightsource is formed by at least one laser diode (9).
 4. A scanner inaccordance with claim 1 , characterized in that an optical transmittingsystem (10, 11) is associated with the light source (9), said opticaltransmitting system (10, 11) transforming a substantially homocentriclight bundle into a substantially linear light beam focused on theobject plane (12).
 5. A scanner in accordance with claim 4 ,characterized in that the intensity of the linear light beam along theilluminated line is largely constant.
 6. A scanner in accordance withclaim 1 , characterized in that the optical transmitting system (10, 11)consists of refractive, diffractive and/or holographic elements.
 7. Ascanner in accordance with claim 1 , characterized in that the lightsource (9) and/or the optical receiving system (7) are movably held inthe housing to set different distances between the scanner and the imageplane (12) (reading distances) and/or different code sizes and areadjustable at different positions.
 8. A scanner in accordance with claim1 , characterized in that the movements of the light source (9) and theoptical receiving system (7) are mechanically correlated with oneanother.
 9. A scanner in accordance with claim 1 , characterized in thatthe optical receiving system (7) is displaceable along its optical axis(A).
 10. A scanner in accordance with claim 1 , characterized in thatthe light source (9) is pivotable in a first plane which extends atleast substantially parallel to the optical axes of the opticaltransmission and the optical receiving systems (7, 10, 11).
 11. Ascanner in accordance with claim 10 , characterized in that the lightsource (9) is pivotable in a second plane substantially perpendicular tothe first plane which includes the optical axis of the opticaltransmitting system (10, 11).
 12. A scanner in accordance with claim 1 ,characterized in that two units are provided in the housing (1), eachcomprising one light source (9) and one optical transmitting system (10,11), with their optical axes positioned at an angle to one another. 13.A scanner in accordance with claim 12 , characterized in that the twolight sources (9) are adjustable with respect to each other and withrespect to the optical receiving system (7) such that they illuminateline regions in the image plane which are aligned to one another andwhich are adjacent to one another or overlap one another.
 14. A scannerin accordance with claim 1 , characterized in that the light receiver(5) is formed as a CCD array, a CCD area, or a CMOS array or a CMOSarea.